As described in U.S. Pat. No. 4,501,185, granted Feb. 26, 1985 to one of the inventors named in this application, Steven Blucher, electromagnetic pickups are used with stringed musical instruments, such as electric guitars, to convert the vibrations of "picked" strings into electrical signals for subsequent amplification into sound. The pickups usually comprise a magnet system, including one or more permanent magnet elements and one or more pole pieces made of magnetic or ferromagnetic material to establish a magnetic field within which the strings vibrate, and coils wound on one or more bobbins disposed in the field to generate electrical signals corresponding to flux variations in the field due to the strings' vibrations. These electrical signals are amplified into musical sounds by circuits and equipment well-known to those skilled in the art.
Although the embodiments presented herein include pole pieces, it should be understood by those skilled in the art that one or more permanent magnets may be positioned within the pickup's bobbin body or bodies, in a manner such that the top and bottom edges of the magnet constitute different polarities, without the necessity of pole pieces of any kind. Furthermore, where pole pieces are used and constitute actual magnet devices, it is known in the art that a separate permanent magnet element is not necessary to create the magnetic field.
Typically, where pole pieces are used in the pickup implementation, they are disposed through holes in the bobbins and the pickup itself is generally mounted on the face of the instrument so that at least one pole piece is situated below each string. The bobbins are arranged so that the pole pieces are within the coils to allow the magnetic field developed by the pole pieces and/or permanent magnet to envelope the coil. Each string, when set into motion, causes variations in the magnetic field in the vicinity of the pole piece or pieces and the variations are converted into electrical signals by the interaction of the magnetic field with the coil.
It is generally understood by those skilled in the art that the efficiency of an electromagnetic pickup is measured by how much output voltage can be produced with the smallest amount of impedance, resistance and inductance. Unfortunately, pickup efficiency has often been sacrificed in the prior art due to other concerns. For example, as discussed in U.S. Pat. No. 5,530,199, granted Jun. 25, 1996 also to Mr. Blucher, the introduction of a second coil to cancel hum in a standard hum-cancelling pickup is accompanied by an increase in resistance, impedance and inductance, thus reducing the efficiency of the pickup.
A common complaint regarding the tonality of electric guitars (as well as other electronic stringed instruments) is that the sound produced is too harsh. This harshness is particularly evident at higher pitches. One way of eliminating or reducing the harshness has been to increase the number of turns of wire in the coil or coils. However, doing so also increases the inductance, resistance and capacitance, resulting in a higher impedance of the pickup. This has the undesirable result of reducing the pickup's efficiency and dulling the instrument's tonality, especially at the lower pitches.
While it is known in the prior art that the inductance of a magnetic transducer (or pickup) will have a direct bearing on the tonality or sound produced by the instrument, no attempt has been made to adjust the amount of inductance of a pickup, independent of the other parameters which contribute to the impedance of the pickup.
It is a primary object of the present invention to provide an electromagnetic pickup having a reduced sonic harshness due to an increased inductance without a corresponding increased DC resistance or capacitance
A further object of the present invention is to provide such results in a hum-cancelling pickup while maintaining the pickup's hum-cancelling capability